A technology enables the imaging of a wide area of a subject within an image by using a wide angle lens having a large angle of view. The technology has been increasingly used in recent years for teleconferences and vehicle-mounted cameras. However, an image obtained with a wide angle lens tends to produce problems such as enhancement of perspective and warping due to distortion (geometric warping) that makes the subject, such as a person, appear warped in the image. For example, when a wide angle lens is used in a teleconference setting, the face of a person in the image may appear warped (problem of distortion) or the person may appear to be sitting farther than where he or she actually is (problem of enhancement of perspective). To address these problems, various correcting technologies have been proposed, including distortion correction and perspective correction (see Japanese Laid-open Patent Publication No. 2001-238177 (“Patent Document 1”) and Japanese Laid-open Patent Publication No. 2009-177703 (“Patent Document 2”), for example).
Patent Document 1 discusses an image processing apparatus capable of performing a predetermined image process, such as gradation control, geometric warping correction, or smoothing depending on an estimated photographed scene, so that high-quality images can be efficiently obtained.
Patent Document 2 discusses an image processing apparatus that corrects a fisheye image having a large distortion into an easy-to-see image by performing coordinates conversion only in the horizontal direction in order to reduce the cost of a photography apparatus.
While the image processing apparatus according to Patent Document 1 is capable of correcting distortion, it cannot eliminate the problem of enhancement of perspective. Further, the image processing apparatus according to Patent Document 2, which corrects for distortion only in the horizontal direction, may not be able to sufficiently correct distortion depending on the photographed scene.